Research in healthy humans over 65 years of age shows greater impairments in learning and memory for olfactory stimuli than visual stimuli. Other studies strongly suggest that problems with remembering and detecting odors may be an early indication of cognitive impairment and Alzheimer's disease. Studies involving aged rats have offered insight into how brain changes associated with aging may result in impaired cognition. However, very little research has examined odor memory in aged rats. The few existing studies investigating odor memory impairments associated with aging in rats have not made direct comparisons with memory for stimuli from a different sensory modality. As a result, it is unknown whether odor memory is any more or less affected by aging than memory for stimuli encoded via other sensory modalities. Therefore, it is unclear whether aging rats are a good model for understanding how age related brain changes might result in impairments in odor memory in older humans. The primary aim of this grant is to investigate the effects of normal aging on memory for olfactory stimuli using an animal model. Specific aim 1 will investigate age- related differences in discrimination and reversal learning for olfactory and visual stimuli. Specific Aim 2 will investigate age-related differences in working memory for olfactory and visual stimuli. Specific Aim 3 will investigate age-related differences in associative learning for olfactory and visual stimuli. The proposed experiments will determine whether odor memory is more affected than visual memory in aged rats. The results of the experiments will offer valuable insight into whether aging has a similar deleterious effect on odor memory in rats and in humans. Furthermore, the findings will suggest whether aged rats are a good animal model for studying the effects of aging on odor memory in older humans. In addition, the results will illustrate how memory for stimuli encoding via different sensory modalities may be differentially affected by aging and how increasing age may differentially affect different types of memory. The findings may have important implications for the selection of memory paradigms for future research studies on aging. The use of an animal model to investigate the effects of aging on odor memory will allow researchers the ability investigate how age-related neuroanatomical and neurochemical changes may result in impaired odor memory.